All about TNS and Making a connection request to an Oracle Database

What happens when an Oracle client issues a request to connect to a database e.g

sqlplus scott/tiger@ora10g.localdomain

Here SQLPLUS is the client program, scott/tiger is the username/password and ora10g.localdomain is a TNS service name. TNS stans for Transparent Network Substrate and is a foundation software built into Oracle client to handle remote connections and allowing peer-to-peer communication. The TNS connection string tells the Oracle software how to connect to the remote database. Generally, the client software will read a configuration file "tnsnames.ora" which contains the details such as hostname, port number and the service name of the database on the host to which we wish to connect. A sample TNS entry:

gaurav_ora =

  (DESCRIPTION =

    (ADDRESS = (PROTOCOL = TCP)(HOST = localhost)(PORT = 1521))

    (CONNECT_DATA =

      (SERVER = DEDICATED)

      (SERVICE_NAME = ora10g)

    )

  )

Here host machine is localhost and "ora10g" is the database service name. 1521 is the port number on which a "TNS listener" process will accept connections.

So now, our client software knows where to connect to. It will open a TCP/IP socket connection to the server with the hostname localhost on port 1521. The TNS Listener process inspects this request and using its own configuration file either accepts or rejects the request.

New Features of Informatica 9.0

Following are some new features introduced in Informatica 9.0 :

1.  New Client tools:

Informatica 9 includes the Informatica Developer and Informatica Analyst client tools.

The Informatica Developer tool is eclipse-based and supports both data integration and data quality for enhanced productivity. The Informatica Analyst tool is a browser-based tool for analysts, stewards and line of business managers.  This tool supports data profiling, specifying and validating rules (Scorecards), and monitoring data quality.

2. Informatica Administrator:

The PowerCenter Administration Console has been renamed the Informatica Administrator.

The Informatica Administrator is now a core service in the Informatica Domain that is used to configure and manage all Informatica Services, Security and other domain objects (such as connections) used by the new services.

The number of objects stored in the domain has increased to accommodate these new requirements.

3.  Session Log size:

You can limit the size of session logs for real-time sessions. You can limit the size by time or by file size. You can also limit the number of log files for a session.

4. Lookup Transformation:

  > Cache updates

     You can update the lookup cache based on the results of an expression. When an expression is true, you can add to or update the lookup cache. You can update the dynamic lookup cache with the results of an expression.

  > Database deadlock resilience

       

      In previous releases, when the Integration Service encountered a database deadlock during a lookup, the session failed. Effective in 9.0, the session will not fail. When a deadlock occurs, the Integration Service attempts to run the last statement in a lookup. You can configure the number of retry attempts and time period between attempts. 

  > Multiple rows return. 

     You can configure the Lookup transformation to return all rows that match a lookup condition. A Lookup transformation is an active transformation when it can return more than one row for any given input row.

 > SQL overrides for uncached lookups

   In previous versions you could create a SQL override for cached lookups only. You can create an SQL override for uncached lookup. You can include lookup ports in the SQL query.